1. Field of the Invention
The invention relates generally to storage devices housing magnetic storage media, and more specifically to single reel cartridges for housing magnetic storage tape and having one or more guide surfaces therein.
2. Description of the Related Art
Digital tape-recording remains a viable solution for the storage of large amounts of data in computer systems. Conventionally, at least two approaches are employed for recording digital information onto magnetic recording tape. One approach calls for moving a magnetic tape past a rotating head structure that reads and writes user information from discontinuous transverse tracks. Interactive servo systems are typically employed to synchronize rotation of the head structure with travel of the tape. Another approach is to draw the tape across a non-rotating head at a considerable linear velocity. This approach is sometimes referred to as linear “streaming” tape recording and playback.
Increased data storage capacity and retrieval performance is desired of all commercially viable mass storage devices and media. In the case of linear streaming tape recording, a popular trend is toward multi head, multi-channel fixed or servo (positioning) head structures with narrowed recording gaps and data track widths so that many linear data tracks may be achieved on a tape medium of a predetermined width, such as one-half inch width tape. To increase the storage density for a given cartridge size, the bits on the tape may be written to smaller areas and on a plurality of parallel longitudinal tracks. As more tracks are recorded on the tape, each track becomes increasingly narrow. As the tracks become more narrow, the tape becomes more susceptible to errors caused from the tape shifting up or down (often referred to as lateral tape motion or “LTM”) in a direction perpendicular to the tape travel path as the tape passes by the magnetic head. In order to maintain proper alignment of the head with the data tracks on the tape, the tape is generally mechanically constrained to minimize lateral tape motion and data retrieval errors.
Lateral tape motion is generally defined as the peak-to-peak distance of the undesirable movement (in-plane) of the tape perpendicular to its prescribed longitudinal direction of motion past a read/write head. Lateral tape motion and the ability to compensate for and reduce lateral tape motion is a major limiting factor in determining the minimum width of a track and the minimum spacing between tracks on the tape. Thus, as lateral tape motion is reduced, more tracks may be stored on the tape and the storage capacity increases accordingly.
Tape substrates are also being made thinner to increase data storage for a given cartridge size. The thinner tape allows more tape to be contained within the same size diameter reel cartridges, e.g., a cartridge about four inches square and one inch high for use with a five and one quarter inch tape drive. Increasing the tape within a given cartridge increases the data storage capacity of the cartridge. Thinner tapes, however, are generally less rigid making them more susceptible to lateral tape motion errors and damage or wear to the tape from the tape drive assembly. For example, guides and rollers that may be used, at least in part, to reduce lateral tape motion and define a tape path through a tape drive adjacent a read/write head may damage edge portions of the tape.
One approach to minimize lateral tape motion tracking errors is to provide a multi-roller tape guide structure within a tape drive, such as the type described in commonly assigned U.S. Pat. No. 5,414,585, entitled “Rotating Tape Edge Guide,” the disclosure thereof being incorporated herein by reference in its entirety. Such an approach may provide a reduction in both lateral tape motion and possible damage to the tape during guiding.
The advent of new head technologies, however, such as magneto-resistive read heads, and new higher coercivity recording media, data track widths have become very small, and many additional data tracks may be defined on the tape. Unfortunately, lateral tape motion remains as a limiting factor, and at certain data track width dimensions and data track densities, it is not possible to follow the tape accurately enough to provide reliable performance during reading and writing operations. Further, as tape thickness is decreased tape edge damage and lateral tape motion become an increasingly greater problem.
Therefore, conventional systems have not been able to keep pace with the increased data storage capacity desired for magnetic tape storage media, including increasingly narrow data tracks and thinner storage media. A need exists therefore for a device and method to reduce lateral tape motion and reduce tape edge damage to potentially allow for increased data storage capabilities.